import numpy as np
import pandas as pd
arr= np.arange(1, 10).reshape(3, 3)
df1 = pd.DataFrame(arr, columns=['a', 'b', 'c'])
df1.insert(0, 'key', ['001', '003', '002'])
print('左对象原始数据df1: \n', df1)
arr2 = np.arange(10, 14).reshape(2, 2)
df2 = pd.DataFrame(arr2, columns=['a', 'e'])